Hi Pop,
Very interesting indeed. A Google search of "Apache TADS" came back with many large and clear pics - and each of the lenses looked different depending on the angle of each indivivual photo. Purple, green, gold and even blacked out in appearance. I'm guessing all the lenses are of the same material, coating, etc. though.
Nevertheless, the lenses look striking, standing out against the surrounding o.d. colour and I don't think you would go wrong with a solid black or gold on the backside of the lense, and then a transparent TINT (of purple, green, red) on the front side.
That's just my suggestion, there may be other ways to acheive an even more realistic result.
Have fun,
Toshi